Experimental realization of a broadband bend structure using gradient index metamaterials.

Following the theoretical work on arbitrary waveguide bends using gradient-index and isotropic materials, a 90-degree bend structure is experimentally realized using artificial metamaterials. Broadband and low-loss unit cells, the I-shaped cells, are used in the laboratory prototype. Field mapping measurement validates the design. The method can be directly and easily extended to the design of directional cloaks, microwave lens, beam shifters, and beam-steering devices.